1. Field of the Invention
The present invention relates to an improved steam drive method of recovering oil from a subterranean, viscous oil-containing formation.
2. Background of the Invention
Steam has been used in many different methods for the recovery of oil from subterranean, viscous oil-containing formations. The two most basic processes using steam for the recovery of oil includes a "steam drive" process and a "huff and puff" steam process. Steam drive involves injecting steam through an injection well into a formation. Upon entering the formation, the heat transferred to the formation by the steam lowers the viscosity of the formation oil, thereby improving its mobility. In addition, the continued injection of the steam provides the drive to displace the oil toward a production well from which it is produced. Huff and puff involves injecting steam into a formation through an injection well, stopping the injection of steam, permitting the formation to soak and then back producing oil through the original injection well.
I have found that the steam drive process for the recovery of viscous oil can be enhanced by injecting steam into the formation while maintaining a certain pressure in the formation near the injection well using water injection and producing oil from the upper portion of the formation.